use git describe --always

[linphone] / mediastreamer2

diff --git a/mediastreamer2 b/mediastreamer2
index 5a7ae95e0dbe5f485086d4635a655c893c9c44b1..8596ed9017c0d9b9c63c758d7628bac1fc07efd7 160000 (submodule)
--- a/mediastreamer2
+++ b/mediastreamer2
@@ -1 +1 @@
-Subproject commit 5a7ae95e0dbe5f485086d4635a655c893c9c44b1
+Subproject commit 8596ed9017c0d9b9c63c758d7628bac1fc07efd7